The Erman Core Laboratory in Cancer Biology has offered support in research methods and instrumentation for investigators in cancer and related research ever since the inception of the University of Chicago Cancer Center in 1973. Ten rooms in the basement of the Erman Biology Center are equipped with three transmission electron microscopes, a scanning electron microscope, freeze-cleave apparatus, and all necessary preparation equipment, including microtomes, evaporators, and instruments for critical point drying and vapor coating. Also available are light microscopes with fluorescence, Nomarski, and interference optics and equipment for single-cell microspectrophotometry, photomicrography, gel scanning, and microcomputerized image analysis. Core laboratory staff members also advise colleagues on methods of immunocytochemistry and other cytochemical methods with their material. When appropriate, exploratory investigations are provided for colleagues contemplating the use of fine structure analysis or cytochemistry in their research. In extensive studies a member of the investigation team is usually involved directly in Core laboratory work. When required, training is provided to personnel in the use of our Core laboratory equipment.